Thursday, October 9, 2014

Scipy.optimization.anneal Problems

Well, not really "problems" per se. More of a strange kind of whining than a solvable problem.

Here's the bottom line. Two real quotes. Unedited.

Me: "> There's a way to avoid the religious nature of the argument. "
Them: "Please suggest away."

Really. Confronted with choices between anneal and basin hopping, they could only resort to hand-waving and random utterances.

The tl;dr summary is this:

"scipy.optimize.anneal only has three hard-wired schedule variants: ‘fast’, ‘cauchy’ or ‘boltzmann’."

My initial response was "And..."?

"Not being able to specify my own cooling schedule severely limits the usability of the code"

A complaint that causes me deep pain: "severely limits" with no actual evidence. And no plan to get evidence beyond a religious wars style argument.There may have been a technical question on the class definitions inside scipy. But that question was overshadowed by the essential problems with what they were doing. Or, more properly, what they were whining about.

Did they really have a problem with a state of the art solution to optimization problems? More specifically:1. Did they read the "Deprecated" part of the scipy documentation? This is a hint that there are better solutions available. Perhaps they could start there instead of whining.2. Did they actually read the details of the three schedules in the "Notes" section? Do they seriously think they've got a new approach that does not fit any of the various parameters of the three installed algorithms? I don't mean to be too rude, but... Do they really think they're that scale of genius?3. Do they have any evidence that their problem is so unlike the typical case handled by basin hopping?4. Do they have any evidence that their solution totally crushes the already-built code?I think the answers to all four question were "no". I'm not even certain that I could help them with some of the Python technology required to extend scipy. But, I'm sure I cannot actually do anything of value under the circumstances that (a) they have not really tried the established algorithms and (b) they're already sure that the established algorithms can't work based on religious-wars arguments.

It was clear that they never read the "Notes" section on this SciPy page: http://docs.scipy.org/doc/scipy/reference/generated/scipy.optimize.anneal.html#scipy.optimize.annealOne of the emails in the exchange had a kind of hand-waving justification for the problem domain being somehow unique. Lacking any actual evidence, I'm inclined to believe they were just hoping that their problem domain was unique, allowing them to dismiss the available Python solution and do something uniquely bad. (Optimization is not my area of expertise. Perhaps I'm way off base; perhaps the existing solutions are so problem-domain specific that everyone has to invent new technology. Maybe established solutions really don't work.)

More importantly: there was no actual evidence that the existing optimization (either annealing or basin hopping) failed to solve their problem.But the worst part was this:"From, a business perspective, I need to know about SA because our competitor stole our biggest client using it."They don't actually want to innovate. They only want to try and catch up by making religious war arguments over the deprecated simulated annealing vs. basin hopping.

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About Me

Steven F. Lott is a consultant, teacher, author and software developer with over 35 years of experience building software of every kind, from specialized control systems for military hardware to large data warehouses to web service API's.